This statement is not enough... there could still be a third party (e.g. law enforcement) with a key or for more plausible deniability, a portion of a key (n bi

This statement is not enough... there could still be a third party (e.g. law enforcement) with a key or for more plausible deniability, a portion of a key (n bits out of N), and the statement would still be true. If they can do so truthfully, they should also state that nobody else other than the user has a key or any portion of a key, and that there are no keys or portions of keys in escrow where anybody else can conceivably get at them.